The Tamron 1.4x SPAF TC (or Kenko pro) works well with the 80-400 VR. Depending on the body and lighting involved AF will be spotty (F100+MB15, D1/D2 series, F5 do better than others). The 80-400 with a 2x TC suffers image quality and usability issues.

I agree with Shun. I tried the 80-400 VR yesterday and while I like the lens I wouldn't use it with a teleconverter - at least not more than a 1.4.

At 400mm with a maximum aperture of f/5.6 it needs fairly bright conditions or, in dim lighting, a reasonable amount of subject contrast, as well as a camera with fast AF to make it work well.

I found the lens fairly difficult to manually focus on my standard D2H screen. It's possible a replacement screen would improve manual focusing capabilities, but I got the D2H for its fast autofocus. I can always use my F3HP or FM2N if I want to manually focus.

If price really is no object, as you indicated (and if so, I envy you!), why not go for a faster prime in the 300mm-500mm range? Since I tend to use telezooms at the longest focal length, I'd rather have the 200/2 VR if I could afford it. Then a 2x teleconverter would be no problem.

<p>I got into this thread a bit late, but I'm in a similar situation although I haven't bought the lens yet. I use a Tokina 400/5.6 and an old manual focus Kenko doubler to shoot really big moons and suns. On a D70 that equates to 1200 mm. Of course you have to have good eye sight to focus accurately, a really dead tripod and a bit of luck to get sharp images.</p>

<p>I willingly trade fast focus and a bright viewfinder for weight and cost. I don't want to afford the thousands of dollars for the fast 400/2.8 tele lens and even if I did, it wouldn't fit in my backpack or in my belt bag. For me, the 400/5.6 is an ideal compromise that fits well in my goals.</p>

<p>After a lot of study, the 80-400 VR will fit even better in my goals. Again, I'm willing to trade the focus speed on the VR and the flexibility of the zoom range. Of course I still will want the occasional big moon or big sun shot. From what I've read, that means the Kenko Pro 2x. No, it won't autofocus, but it will meter and I usually focus manually with the 400/5.6 anyway. Besides, it's the moon; it doesn't need autofocus.</p>